A semiconductor structure comprises a substrate and a source region formed in the substrate. Further, a drain region is formed in the substrate. The drain region comprises a first drain portion with a first doping concentration and a second drain portion with a second doping concentration, which is lower than the first doping concentration. Between the source region and the second drain portion a channel region is defined. Further, a field plate is provided, which is disposed across the junction between the first drain portion and the second drain portion to reduce the gradient of the electrical field at the junction.